JPH06228704A - Contact material for vacuum bulb and its production - Google Patents

Abstract

PURPOSE:To obtain a contact material for vacuum bulb capable of reducing the frequency of occurrence of restrike by forming the contact material for vacuum bulb by bending specific percentages of arc-resisting components, such as Ta, auxiliary components, such as Cr, and conductive components, such as Cu. CONSTITUTION:The contact material for vacuum bulb is constituted of arc- resisting components consisting of 25 to <75vol.% of at least one element among Ta, Nb, W, and Mo, auxiliary components consisting of <=75vol.%, in total with the above arc-resisting components, of at least one element among Cr, Ti, Y, Zr, Co, and V, and the balance conductive components consisting of Cu and/or Ag. This contact material is obtained, e.g. by mixing arc-resisting component powder and auxiliary component powder, sintering the resulting powder mixture in a vacuum atmosphere to form a skeleton, and then infiltrating the conductive components into the skeleton in a vacuum atmosphere. By this method, the high reliability contact material for vacuum bulb where probability of occurrence of restrike is reduced can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact material for a vacuum valve and a manufacturing method thereof.

[0002]

2. Description of the Related Art As the characteristics required for a contact material for a vacuum valve, there are three basic requirements indicated by performances such as welding resistance, withstand voltage and interruption, and in addition, temperature rise and contact resistance are low and stable. Is an important requirement. However, it is impossible to satisfy all the requirements with a single metal because some of these requirements conflict with each other. For this reason, in many practically used contact materials, two or more kinds of elements that complement each other in insufficient performance are combined and suitable for a specific application such as for large current or high breakdown voltage. Although contact materials have been developed, the fact is that there are still some points that are still unsatisfactory for the ever-increasing required characteristics. As a recent remarkable trend, the expansion of the application circuit to the reactor circuit, the capacitor circuit, etc. can be mentioned, and the development of contact materials
There is an urgent need for improvement. Especially in the capacitor circuit,
Due to the fact that a voltage that is twice that of the normal circuit is applied, the problem of withstanding voltage characteristics of the contacts, especially the suppression of re-ignition has emerged.

In order to deal with this, W.Mo.Ta.N, which is a high melting point material which is generally excellent in withstand voltage, has hitherto been used.
A contact material composed of b and Cu which is a conductive component has been applied.

[0004]

Although such contact materials such as Cu-W can be applied to a high withstand voltage field to some extent, they are re-ignition in a more severe high withstand voltage region and a circuit involving an inrush current. There is a problem of occurrence of. The cause of this is that the arc-resistant material is not sufficiently wet with the conductive component, so that the adhesion strength between the particles of the arc-resistant material and the conductive component becomes insufficient.

That is, despite the electrode being in the open state,
The arc-resistant particles are charged and discharged from the contact surface,
Gas may protrude from the pores inside the contacts that are generated due to insufficient wetting, and re-ignition occurs. Furthermore, when local welding due to high-frequency current generated at the time of turning on occurs, the interface strength between the arc-resistant material and the conductive component is weak and the presence of local pores causes the contact surface to come off when the electrode is removed. In some cases, relocation occurs, which causes electric field concentration and the like to cause re-ignition. If the re-ignition occurs, it will spread to the accident of the circuit system and cause a power failure, for example.

As described above, the cause of re-ignition is that the arc-resistant material is not sufficiently wet with the conductive component, and therefore the adhesion strength between the particles of the arc-resistant material and the conductive component is not sufficient. It is important to reduce the frequency of restriking by improving the interfacial strength and reducing the internal pores. An object of the present invention is to provide a contact material for a vacuum valve and a method for manufacturing the same, which reduces the frequency of re-ignition.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention further enhances the adhesion between the arc resistant component and the conductive component by further adding Cr, T to the arc resistant component and the conductive component.
The gist is to add at least one of i, Y, Zr, Co, and V.

That is, by adding at least one of Ti, Cr, Zr, Y, Co, and V to the arc resistant component and the conductive component as the contact material, the adhesion between the arc resistant component and the conductive component is improved. In contrast, the conventional arc-resistant materials such as W could not obtain sufficient interfacial strength because they did not form a solid solution and react with Cu, whereas the contact material of the present invention also reacted with arc-resistant materials. This is because an auxiliary component that reacts with the conductive component is added. Therefore, the arc-resistant component and the conductive component are bonded more closely, and the discharge of arc-resistant particles from the surface, the occurrence of remarkable irregularities when welding occurs, and the reduction of pores inside the contact point are realized. The generation of arcs can be suppressed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a vacuum valve, and FIG. 2 is an enlarged view of an electrode portion of the vacuum valve.

In FIG. 1, a shut-off chamber 1 includes an insulating container 2 formed of an insulating material in a substantially cylindrical shape, and metal lids 4a and 4 provided on both ends of the insulating container 2 via sealing metal fittings 3a and 3b.
It is configured to be kept in a vacuum with b.

A pair of electrodes 7 and 8 attached to opposite ends of the conductive rods 5 and 6 are arranged in the shutoff chamber 1. For example, the upper electrode 7 is a fixed electrode and the lower electrode 8 is movable. It is used as an electrode. A bellows 9 is attached to the conductive rod 6 of the electrode 8 to allow the electrode 8 to move in the axial direction while keeping the shut-off chamber 1 vacuum-tight. An arc shield 10 made of metal is provided on the upper portion of the bellows 9.
Are protected from being covered with arc vapor. Further, a metal arc shield 11 is provided in the shut-off chamber 1 so as to cover the electrodes 7 and 8, and thereby the insulating container 2 is prevented from being covered with arc vapor.

On the other hand, as shown in FIG. 2, the electrode 8 is fixed to the conductive rod 6 by the brazing portion 12 or is crimped by caulking. The contact 13a is attached to the electrode 8 by brazing 14. The same applies to the electrode 7.

Next, an example of the method of manufacturing the contact of the present invention will be described. The contact material manufacturing methods are roughly classified into
There are an infiltration method in which a conductive component is melted and poured into a skeleton made of arc-resistant powder and the like, and a sintering method in which powder mixed with a predetermined composition is molded and sintered.

The manufacturing method of the present invention is characterized by the following points as compared with the conventional method. That is, in the case of the infiltration method,
A skeleton is manufactured by, for example, sintering in a vacuum atmosphere with a mixed powder of arc-resistant powder and a third element powder (auxiliary component powder), and a conductive component is infiltrated into the skeleton in a vacuum atmosphere to form a contact. This is the point of production. The contact can also be manufactured by infiltrating a skeleton made of only arc-resistant powder with a conductive component containing the third element. In the case of the sintering method, the contact is manufactured by, for example, sintering a mixed powder of a predetermined amount of arc-resistant powder, conductive powder, and third element powder in vacuum. In either case of the infiltration method or the sintering method, it is possible to manufacture contacts by using a powder obtained by coating the arc-resistant component powder with the surface of the third element or an alloy powder of the arc-resistant element and the third element. is there. Next, an evaluation method for obtaining a specific example described later,
The evaluation conditions will be described.

Against the background as described above, the contacts of the present invention and the conventional contacts were compared at the frequency of re-ignition. Diameter 30
mm-thick, 5 mm-thick disc-shaped contact piece is attached to a demantable vacuum valve, and a 6KVx500A circuit is installed in 2000.
The frequency of re-ignition when the circuit was interrupted once was measured, and two circuit breakers (six valves) were measured and shown as the rate of re-ignition. When attaching the contacts, bake (450 ° C
x 30 minutes), and the brazing filler metal and the heating associated therewith were not performed.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

In the production of Tables 1 to 3, a single metal powder is used. The skeleton of the infiltration method was made only of arc resistant powder and auxiliary component powder, and oxygen-free copper and vacuum-melted Ag / Cu alloy were used as the infiltration material. Example 1-3, Comparative example 1-2 (see Table 1)

With the Nb content of the arc-resistant material being constant at 25% by volume, the amount of Cr added as an auxiliary component is 0.1, 25, 50, 6
A contact of 5% by volume was manufactured (Comparative Example 1, Examples 1, 2, 3 and Comparative Example 2, respectively). A mixed powder of Nb powder and Cr powder was used as the raw material powder. Comparative Example 1 and Example 1 were manufactured by the sintering method. Specifically, it was manufactured by mixing and molding Nb powder, Cr powder, and Cu powder, and then sintering at a predetermined temperature. Examples 2, 3 and Comparative Example 2 were manufactured by the infiltration method.
Specifically, Nb powder and Cr powder are mixed, molded, and sintered to produce a skeleton. Then, oxygen-free copper was infiltrated into a test piece. These test pieces were processed and incorporated into a demantable chamber to measure the probability of re-ignition.

As a result, as shown in Table 1, in Comparative Example 1 in which Cr was not added, the probability of re-ignition was 1-2%, while 1,25,50% of Cr was added. Example 1,
Nos. 2 and 3 were 0.5-0.8% and showed an improvement tendency.
Also in Comparative Example 2 in which Cr was added by 65%, the probability of re-ignition was 0.
Although it was improved to 8%, the contact resistance was large and it was difficult to put it to practical use probably because the conductive component was small. An Nb-Cu contact made by the infiltration method without Cr addition was also manufactured for comparison, but could not be infiltrated probably due to the influence of surface oxidation. Example 4-6, Comparative Example 3-4 (see Table 2)

With the addition amount of Ti of the auxiliary component being constant at 1% by volume, the Ta content of the arc-resistant component is 15, 25, 50, 70,
90% by volume of contacts were manufactured (Comparative Example 3, Examples 4, 5, 6 and Comparative Example 4, respectively). The manufacturing method of the contact is Comparative Example 3
And Example 4 are the same sintering methods as those of Comparative Examples 1 and 1 described above, and Examples 5, 6 and Comparative Example 4 are the same infiltration methods as those of Example 2. The probability of re-ignition for all test pieces was 0.5.
-0.8%, showing improvement, but Ta content 15
%, Comparative Example 3 had a significant decrease in the blocking ability, and Comparative Example 4 having a Ta content of 90% had a large contact resistance like the above Comparative Example 2 and could not be incorporated into a practical valve. Examples 7-8 (see Table 3)

Table 1 shows Nb-Cr-Cu system, and Table 2 shows T.
An example of the a-Ti-Cu system has been described, but not only Nb / Ta but also W / Mo as an arc-resistant material, and Y / Zr / Co / V and C as well as Cr / Ti as auxiliary components.
Even if Ag which can be a conductive component is used instead of u, the probability of re-ignition can be similarly reduced. Example 7 is 50% by volume
A contact of W-5% Co-30% Cu-15% Ag was manufactured by the infiltration method, and Example 8 was 25% W-25%.
The contact of Mo-Y-1% Zr-Cu is manufactured by the infiltration method. Probability of re-ignition is 0.8 at each contact
It was confirmed to be as small as 0.5% and 0.5% and useful.

From the examination results of the above examples, not only the composition of this example but also Ta, Nb, Mo, W as the arc-resistant material, Cr, Ti, Y, Zr, Co, V as the auxiliary component, and the conductive component It is obvious that the frequency of re-ignition can be reduced by using Cu.Ag for the. Examples 9-12 (see Table 4)

Next, the manufacturing method will be examined. In Example 9, Nb powder and Cr powder were mixed and mixed at a ratio of 9: 1, and then oxygen-free copper was infiltrated to produce a contact.
In Example 10, after manufacturing a skeleton using only Nb powder,
It is an infiltrated 2% Cr-Cu alloy produced in advance. Example 11 is a skeleton produced by mixing and sintering Nb / Cu alloy powder and Cu powder, and newly infiltrating oxygen-free copper. Example 12 is Cr with Nb
The contact is manufactured by mixing and molding the surface-coated powder with Cu powder and sintering the mixture. The probability of re-ignition of these contacts was 0.5-0.8%, which was a good result.

When observing the cross-sectional structure of the contact material manufactured by these various manufacturing methods with an optical microscope and an electron microscope, the auxiliary component tends to be surrounded by the arc resistant material, and the auxiliary component has the arc resistant property. It was confirmed that the material plays a role of binding between the material and the conductive component. In particular, this tendency was remarkably recognized in the contact material manufactured by the infiltration method. The result shows that the probability of re-ignition of the contact material produced by the sintering method is about 0.8%, whereas that of the contact material produced by the infiltration method is 0.5%. It can be estimated that it also reflects. Therefore, when manufacturing the contact material by the sintering method, it is desirable to set the sintering temperature to the melting point of the conductive component or higher. Even if the melting point is lower than the melting point, it is better to approach the melting point as much as possible to cause re-ignition. It is effective in suppressing. However, the sintering method is also sufficient for reducing the probability of re-ignition.

When the cross-sectional structure was observed toward the conductive matrix, the melted or broken portion of the auxiliary component was observed in various places inside the conductive component matrix, and it was confirmed that the auxiliary component and the conductive component were firmly bonded. did it. This phenomenon was also remarkably observed in the contact material by the infiltration method.

From the examination results of the above examples, it is apparent that the manufacturing method of the present invention is not limited to this example, and similar results can be obtained by a partial combination of the examples.

[0030]

As described above, according to the present invention, the auxiliary component improves the adhesion strength between the arc-resistant component and the conductive component.
It is possible to obtain a highly reliable contact material for a vacuum valve having a reduced probability of re-ignition and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a sectional view of a vacuum valve to which a contact material for a vacuum valve of the present invention is applied.

FIG. 2 is a partially enlarged sectional view of FIG.

[Explanation of symbols]

 7, 8 ... Electrodes, 13a, 13b ... Contacts

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01H 33/66 B 8121-5G

Claims (9)

[Claims] 1. An arc-resistant component comprising 25% by volume or more and less than 75% by volume and comprising at least one of Ta, Nb, W, and Mo, and the total amount of the arc-resistant component is 75% by volume or less. A contact material for a vacuum valve, which has an auxiliary component made of at least one of Cr, Ti, Y, Zr, Co, and V, and a conductive component made of at least one of Cu or Ag. 2. The contact for a vacuum valve according to claim 1, wherein the auxiliary component is formed so as to surround the arc-proof component, and the conductive component is contained as a conductive component matrix. material. 3. The contact material for a vacuum valve according to claim 1, wherein the arc resistant component and the auxiliary component are alloyed and the conductive component is contained as a conductive component matrix. 4. The arc-resisting component powder, which is 25 vol% or more and less than 75 vol% and is made of at least one of Ta, Nb, W, and Mo, and the total amount of the arc-resisting component powder is 75 vol%. The following is a skeleton made of a mixed powder or a composite powder with an auxiliary component powder consisting of at least one of Cr, Ti, Y, Zr, Co, and V, and the infiltration material is infiltrated into the skeleton. A method for manufacturing a contact material for a vacuum valve, comprising: 5. The contact material for a vacuum valve according to claim 4, wherein the skeleton is made of a mixed powder or a composite powder of the arc resistant component powder and an auxiliary component powder, and a conductive component powder. Production method. 6. The method of manufacturing a contact material for a vacuum valve according to claim 4, wherein the infiltrant is at least one of Cu and Ag. 7. The infiltrant is Cr, Ti, Y, Zr,
Cu or A containing at least one of Co and V
6. The method for producing a contact material for a vacuum valve according to claim 4, wherein the contact material is at least one of g. 8. The arc-resisting component powder, which is 25 vol% or more and less than 75 vol% and is made of at least one of Ta, Nb, W, and Mo, and the total amount of the arc-resisting component powder is 75 vol%. The following is mixed with a mixed powder or a composite powder with an auxiliary component powder consisting of at least one of Cr, Ti, Y, Zr, Co and V, and the balance of a conductive component powder consisting of at least one of Cu or Ag. A method of manufacturing a contact material for a vacuum valve, which is characterized by being formed and then sintered. 9. The vacuum valve according to claim 4, wherein the composite powder is obtained by coating the arc resistant component powder with an auxiliary component powder. Method of manufacturing contact material.